Pre-open files attack agains locked file

Type securityvulns
Reporter Securityvulns
Modified 2007-03-10T00:00:00


Hello lists, hello Roger. It's me again.

Sorry for annoyance, but there is one more attack vector with pre-open files I meant, but forgot to mention. It seems dangerous enough and need to be investigated for different applications. Attack is against application relying on mandatory locks.

Attack scenario:

  1. Alice pre-opens some Document and awaits Bob to open it. Document is safe to open (text file, video file, business application format, etc). Also, like in case of Microsoft Word it can be temporary file.
  2. Bob opens Document with some Application.
  3. Application locks file and reads or writes some data
  4. Alice modifies data
  5. Application reads previously accessed data. Because application relies on the fact data can not be modified in locked file, this data is not validated. It can lead to the problems like buffer overflows and to ability to modify execution flow and to arbitrary code execution.

What can be instead of Application? Any application to process user supplied file which locks this file during processing.

Examples are: Microsoft Office applications, video/audio players, etc. I expect huge number of applications are vulnerable and will be grateful to everyone who can help me to find this kind of vulnerabilities in-the-wild, because this kind of vulnerability is not trivial and hard to catch without source code analysis.

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